1. Technical Field
The invention concerns improved trick mode playback, and more particularly to improvements in the trick mode playback of an audio content associated with a video segment played back at a faster or slower than normal speed.
2. Description of the Related Art
DVD trick modes can include speedup or slowdown of normal playback to either search for a specific location on the disc or to look at details of a video sequence that would normally be missed at regular speed. Both audio and video trick modes are possible and both are found on DVD players that are commercially available. However, conventional methods for playback of audio at fast or slow speed have proved to be problematic. The advancement of the audio digital signal processors used in currently available products has created the possibility for more sophisticated real-time processing for improved audio trick modes.
One problem with the use of video trick modes concerns the treatment of the corresponding audio content. For example, when a user seeks to speed up or slow down the video images displayed, audio playback will be rendered unnatural or distorted. The audio programming is shifted to higher frequencies when a fast trick mode is used, and to lower frequencies when a slow trick mode is used. A fast trick modes that increases the playback speed by a factor of between about 1.5 to 3 times as compared to normal playback will tend to cause human speech to sound higher in pitch. This higher pitched audio playback can be annoying and in many instances is not intelligible to the listener. Conversely, slow speed trick modes produce a lower frequency wobbling sound that may be understandable but not very acceptable to the listener.
Many commercially available DVD players now include a karaoke processor integrated circuit. These processors offer karaoke features in addition to the basic DVD player functions. Basic features of karaoke processors include voice cancellation, echo, and key control. Voice canceling filters out vocal content, allowing a user to sing along. The echo function slightly modifies a singer's voice to enhance the sound. Key control adjusts the pitch of the music to match the pitch of the singer. Such processors have the potential to be useful in addressing some of the problems encountered when reproducing audio during trick mode operation. Heretofore, however, the processing capabilities of these circuits have not been applied to address the problem of audio associated with video trick mode playback.
To avoid the acoustic oddities resulting from DVD trick modes, conventional DVD players often mute the audio during trick mode replays. However, this is not an entirely satisfactory solution since the audio may be of interest in such modes. Accordingly, it would be advantageous if a DVD player could playback audio in a manner that overcomes the limitations of the prior art and provides an audio trick mode playback that is more useful for the listener.